We have been doing a lot of work on spacelaunch “infrastructure” systems and hardware. The basic hardware to support serious spacelaunch development deserves its own topic, since it will be needed by most teams. If you happen to live near Edwards Air Force Base, and have a working relationship with those people which will motivate them to use their high resolution video tracking system and ultra precision radar to track your flights, then you may not need to do develop these systems. Many of us watched through these systems as SS1 set altitude records.

It is easy to forget that such tracking systems are neither affordable not readily available. Those who are still struggling to static test rocket motors may not have considered just how difficult it will be to debug the in-flight problems which will appear when their development moves off the ground. Anyone who has flown Radio Control Airplanes (known in the military as UAVs) knows that a whole lot of development work remains to be done in a custom design after the motor is running!

This interacts strongly with the spacelaunch licensing issues as well, including insurance costs. The only reason that spacelaunch is permitted from the Florida coast, is that those rockets (including the Shuttle) have thoroughly proven flight control and flight termination systems that make it EXTREMELY unlikely that the rocket will accidentally land in Miami!

With our series of 15 liquid fueled rocket flights, we have made good progress with flight tracking and documentation, as well as “telemetry” to capture data and let an un-recovered flight produce good engineering results. Major improvements to our interferometric, radio tracking systems are nearing completion, and will be reported soon.

I confess to wondering if I am crazy, or if other people are. We have spent a lot of time perfecting systems which other people don’t even talk about. Several teams are promising manned flights “real soon”, without having done unmanned flights, or even creating the basic tools to generate meaningful results from unmanned flights! Thank God for John Carmack and the Armadillo team! Their well documented development process assures me that the similarly slow and troubled progress we are achieving is OK. This leaves big questions about the teams which report no such problems (because of no relevant tests?). (Obviously this doesn’t apply to secretive Scaled Composites. Beyond their visible results, the one hundred thousand man-hours of skilled services their funding paid for – combined with the quality of the people they employ – was clearly used to work through a lot of challenging problems and details. A few of these are identifiable in the “Black Sky” videos.)

Back to the flight test systems themselves, I find it frightening to consider manned flight in a vehicle I have not been able to observe and photograph in unmanned tests. (I can’t even imagine flying in a completely untested design, which means the unmanned tests must be done first.) Telemetry is useful, but even with Space Shuttle Columbia, amateur telescope pictures provided more information! But photography of aerospace vehicles tens of miles distant is far from trivial! Without hope of free help from Edwards Air Force Base (or the Clay Center for Science and Technology – prep school), we have made steady progress with our own systems.

With ground launched rockets in particular, the launch generates a smoke or vapor cloud which virtually guarantees that visual track on the rocket will be lost at some point. A more distant observer may be blessed with a cloudless view – but I wouldn’t bet on it. This means that precision radio tracking (radar or telemetry related) must be used to guide the cameras. The cameras themselves are far from ordinary. The Moon looks big, visually, but produces only a ½ to 1/3 millimeter spot on the film of a standard 35 mm camera. Yet, at one hundred miles slant range from a spaceflight, this same image spot represents one mile of sky. Increasing the camera focal length to 2500 millimeters (50 times normal) fills the frame height with the Moon (or that one mile portion of the sky). This extreme telephoto lens, at that distance, would produce a usable photo of an aircraft supercarrier (1/8 the width of the frame)[2 milliradians], but the SpaceShipOne is 60 times smaller [30 microradians = 6 sec arc]. The later is one sixth the apparent diameter of the planet Saturn with its rings, so it is obvious that a very good telescope and robotic tracking system are required to get the quality of pictures which were broadcast for SS1.

Testing the optics of these systems is easy. The planet Jupiter is about as bright as the Moon, and both are easy to see overhead in a clear blue sky. If you don’t think it is easy to find Jupiter in the daytime sky, then you begin to have an understanding of the spacecraft imaging problem. (It is easier to image the Shuttle or ISS at night, against a black sky, but launches are safer in daylight.)

Before I climb into my spacelaunch system I want to get a very good look at how the vehicle handles its transition from aerodynamic flight to spaceflight. This transition is particularly “interesting” when it is still powered. Minute thrust vector errors will cause the craft to tumble – which leads to the requirement of active “thrust vector” control. This is the unmentioned third control system which kept Melville and others really busy in the SS1. This critical transition occurs from 100,000 ft to 150,000 ft (1% to 0.1% atmospheric density). A SS1 sized craft at that altitude will approach the apparent diameter of Jupiter, or Saturn with its rings. Thus a good telescopic system, able to clearly resolve Saturn’s rings in daytime, will also allow studies of spaceship pitch and roll at this point in its flight.

We have the DIT (Dynamic Imaging Theadolite) system necessary to properly position such a “camera”, and have built many suitable telescopes. It would be much better to locate this system on a solid foundation, but portable and marine versions are feasible. This is one of the systems we will have before we begin manned high altitude flights. I wonder what other teams are going to use?

I really think it's normal to test that much, I'm also wondering how some other teams are going to do that much in such very short time.
In case of Scaled Composites, they have a large workforce, if really needed they could put more than 100 people on it and still don't have all employees working on the project.

But I don't think AERA Space, Canadian Arrow etc have such a large teams..

In the prior post I mentioned radio tracking to guide a telescopic camera. Precision radio tracking is one of the areas we have been concentrating on, with many good results. Guiding a camera is only one of the radio tracking benefits: it provides additional information to characterize a flight (often the best information - plotting three dimensional position with time); it increases the likelihood of vehicle recovery (by no means guaranteed for high altitude flights); it can be used as part of guidance protocols; and it is required for FAA licensed flight testing of anything that could become a manned rocket!

The FAA and DOD standard for guided rocket tests is that three independent tracking systems be used: most or all of these will be radio tracking systems so that smoke or a cloud will not force flight termination. These are part of the “Flight Safety System”. A spinning, unguided rocket can have a fairly predictable flight path (with increasing spin tightening up the predicted landing zone). If you or your passengers won’t spend hundreds of thousands of dollars to see the world spinning around several times a second, then this won’t work for you. An unguided rocket with a mechanism to counteract its natural tendency to spin will have a very unpredictable flight path, often hitting the ground while still accelerating. (Another thing your passengers won’t like.)

This is counteracted by a guidance system. However, as soon as you put a guidance system on your rocket, you are required to provide a Flight Termination System (FTS). Even minor errors in your guidance system radically enlarge the possible impact zone. Since a rocket capable of reaching even 70 mile altitude (112km) can land anywhere within 140 mile radius (over 61,000 square miles) a lot of people and private property can be endangered. The multiple, redundant tracking systems guarantee that guidance failures are detected early. You will have had to prove that in all conceivable circumstances and failure modes your Flight Termination System and protocols will reduce the risks to people on the ground to a very low (part per million) level. Note that for experimental systems, the FAA starts by assuming a 50% probability of vehicle failure. (A lot of flight tests will be needed before even a 1% failure rate is conceivable for safety calculations). Your business plan probably requires that you think about the safety of people on the rocket as well.

Radar is one allowable tracking system, if you have a calibrated and highly reliable system near your launch site. The FAA Air Traffic Control may be able to help here. But what are you going to do for two or more additional systems? For safety purposes, the tracking accuracy doesn’t need to be better than 1 degree, which is typical of a good airport radar. This isn’t nearly good enough to guide the telescope or to provide good flight test data, but it is still no mean accomplishment. At microwave frequencies, antennas 1.8 meters wide (X band) to 6 meters wide (S band) can provide this beam width. With continuous sweep, antennas somewhat smaller than this can give the 1 degree azimuth accuracy. Phase switching segments of an X band antenna less than 0.5 meters in diameter can exceed this resolution in both altitude and azimuth and do so in a “staring” mode. This type system is used in the F-15 and F-16 fighters.

For a number of reasons (discussed later), lower frequencies have many advantages. This multiplies the needed antenna sizes. The 1.8 meter X band antenna grows to over 36 meters (120 feet) at 450 MHz (not my idea of a portable system). And this antenna system still needs to be rotated to provide the 1 degree resolution in one axis (no resolution in the altitude axis).

Fortunately interferometry can be used to make this system practical. This is related to the phase switching technique mentioned above, and is also related to the difference between a flashlight and a laser, or that between a camera and a hologram. In all of these the radiation must be highly predictable (called coherent) so that the actual phase or temporal oscillations of the radiation can be measured and controlled. Once this is achieved, it becomes possible to improve the detection accuracy by several orders or magnitude. Distance measuring with light shrinks from millimeters to nanometers – even below the diameter of an atom. Angular measuring with radio waves – what is needed for this application – allows a trailer mounted antenna (at 450 MHz) to locate a rocket to one thousandth of a degree in both altitude and azimuth. This is one of the systems we have been working on and have in operation.

This resolution is more than sufficient to guide a high resolution video camera (which will have a field of view of about 0.05 degrees), and to track the rocket second by second to 2 foot resolution at the critical 20 mile altitude. Even better distance resolution is obtainable with our coherent telemetry systems. This work does take some unique hardware, particularly the multichannel, phase coherent radio systems, as well as the precision phase analyzers, and telemetry data strippers.

We have spent time and money on this development which could have gone into testing bigger rocket motors. But as noted, I am not prepared to take off in a rocket with undocumented performance. Precision radio tracking and linked imaging systems are standard features at established “Instrumented Test Ranges”, but the million dollar costs for a handful of flights at these facilities don’t fit well into my budget. As noted elsewhere, we are prepared to offer use of these systems to other teams when and if they become serious about flight testing.

I apologize for the complexity of this presentation. State of the art work in any specialty is hard to communicate. I mentioned previously that recording the phase of scattered coherent light produces a hologram. A closely related technique with radio waves is Synthetic Aperture Radar (SAR) which could be called “RADAR Holography”. Many have seen the astonishing surface detail captured with this technique. Another related process is ISAR (Inverse Synthetic Aperture Radar), which is used when the target is moving and the radar system is fixed in position. These results are not so widely published, as they are used for antiballistic missile target discrimination and other high resolution target discrimination needs.

An understanding of the theory or details is not necessary: what is necessary is to understand is that these techniques work. The “one thousandth” degree resolution mentioned earlier is not always obtainable, and requires great care to approach. However this resolution is often overkill. A fraction of this resolution allows tracking small (FAA exempt) probes in violent storm systems. Similarly, only a fraction of this resolution is necessary to guide a rocket for orbital insertion, or orbital rendezvous. The use of external tracking radically simplifies the vehicle systems that would be necessary for self contained, “inertial guidance”. And of course, short term, these systems produce laboratory quality data to document the flight of suborbital vehicle tests!

Personally, I have been involved in coherent, phase sensitive systems work for over forty years, including applications in Radio Astronomy, Acoustic Holography, Holographic Interferometry and collision avoidance systems. I have been awarded patent protection for some of these techniques. We now have a number of operational systems which use these techniques to document rocket test flights.

One weakness of interferometric processes is a sensitivity to reflected, or “multiple path” signals. This is an even bigger problem with compact “directional Loop Antennas”, but a lesser problem with large RADAR antennas. Our “RotoTrack”™ system (described in a press release) was developed to address this weakness. This is a hybrid system, combining directional antennas with continuous rotary motion like a RADAR, but integrating interferometric signal processing to produce far more precise directional information. We believe that this system – when used from two offset locations – will provide triangulated data sufficient for FAA required “Flight Safety” use even in the presence of reflected signals. It will also identify the presence of such error producing signals, and allow estimation of the errors. When the errors are small and correctable, the interferometric mode will produce the precise directional information needed to guide a camera. Note that although these are passive systems, tracking small radio transmitters on the rocket, each such unit can simultaneously track two or more independent transmitters on the rocket for redundancy and reliability. The actual FAA flight safety requirements will of course depend on the launch site to be used, and on the test vehicle characteristics.

We see little alternative to having systems such as these in place, with certified calibration and reliability data, before high altitude flight tests can begin. Thus we have invested a great deal of effort into these infrastructure components. As usual with infrastructure, the results aren’t “sexy” and don’t excite investors – but still need to be in place before the goals can be reached.

Where are you going to conduct high altitude flight tests of your launch system? Even with proven “Flight Safety Systems”, Murphy might show up and allow your rocket to climb high – off course!

A 165,000 Acre rocketry site in west Texas is impressive, but it is also TOO SMALL! It could barely contain a 9.05 mile radius “flying field” (18.117 Mile Diameter), and a rocket flight capable of reaching 24,000 feet (4.5 miles) could fly outside this zone. If you plan to fly over 4.5 miles high (rather less than “space”) there is a good chance that your rocket – or its pieces in case of “energetic disassembly” - will land on neighboring private land. You might do a lot of damage on that neighbor’s land. More to the point, that neighbor might CLAIM you did a lot of damage, destroying his million dollar cultivation of wildflowers, or his five million dollar prize bull. You get to prove in court that an animal carcass really couldn’t have been a prize bull, even when the landowner swears it was, or that the exhibited piece of rocket didn’t actually kill it. You get to prove this to a jury who hates the idea of rocket debris landing on their cattle, or dogs or children. (Remember to factor punitive damages into your financial risk calculations.)

If you fly rockets capable of reaching 70 mile altitude, your rocket debris could be scattered over 61 thousand square miles of private land! Assume that this represents the spreads of one thousand BIG landowners – the kind who retain good lawyers! Some of them don’t like your kind of people (whatever that may be). Some of them like the idea of making money (and they didn’t get rich passing up opportunities). Some of them actually have a bunch of problems – and you just provided a way to get rid of ugly debts!

I know that nothing will go wrong in your flight tests (it only happens to other people – and NASA), but your insurance company may not agree, and FAA licensing has “fiscal responsibility” provisions. A TGV quote included: "Amateurs talk about propulsion. Professionals talk about insurance." And this is absolutely true! If the Southwest Spaceport included all the land over a 140 mile radius (in New Mexico, Texas a bit of Arizona and a big chunk of Mexico) you might be able to ignore the possibility of private landowner suits, as long as you don’t make your rocket capable of higher flight. But no spaceport includes that amount of land.

There is only one way to keep our experimental rockets off private land and that is to launch offshore. Your test might still land on a boat, but that chance can be reduced to less than one in a million. If you launch over land your chance of landing on private property can approach 100%! So get used to the idea of launching from a boat – I plan to do exactly that, with all the telemetry tracking and control systems operating from marine platforms.

We have the respirator masks for our life support experiments and manned flight tests in operation. This is an adaptation of an industrial, supplied air breathing mask. Our modification is a “three port” design, with intake on the left side, exhaust on the right side and an extra port in the middle. This extra port can be used for water, food, “cleanout” (saliva, mucus and vomit) as well as for emergency breathing air supply. We expect to be working with some level of positive pressure so that “open mask” procedures would be very risky. We expect that emergency “buddy breathing” modes will be feasible, even in orbital EVA. A microphone is also being prepared, which may be wired through this middle port as well.

All of our work will be done with “rebreather” systems, including multiple Oxygen partial pressure sensors, and CO2 scrubbers. Several “permanent” CO2 scrubbers are practical, including the thermally regenerated “Silver Hydroxide” absorbers. Rebreathers reduce the Oxygen supply needed in EVA and similar orbital uses by a factor of at least 5, and reduce the consumption of Oxygen during “prebreathing” periods by a factor of 25. An undersized, 25 cubic foot SCUBA tank filled with Oxygen would supply a user for two full days. On the other hand, a single liter of LOX (Liquid Oxygen) will do the same.

It became clear in 2002, while planning the hardware necessary for manned flight tests, that the life support and safety systems would need considerable effort. The NOISE level close to high thrust rockets demands serious hearing protection, as well as noise rejection systems for reliable voice communications (we are not finished with these systems). The dust and exhaust fumes are of course also unbreathable. (The “hard shell” crew compartment planned by others carries a large weight penalty, and still may not address life support needs for long delayed launch preparations.) All of these are factors safely ignored with light aircraft.

We also plan to use full cabin CO2 flooding for firefighting, high flow water spray for launch pad firefighting and allow deep water recovery as an option. Each of these makes SCUBA type, underwater breathing desirable and this is our design philosophy.

With these masks now in operation, we are also ready to continue the life support work outlined for Mars Missions.